The OsWRKY63-OsWRKY76-OsDREB1B module regulates chilling tolerance in rice

Area of Science:

• Plant Molecular Biology
• Plant Physiology
• Genetics

Background:

• Rice (Oryza sativa) is susceptible to low temperatures, impacting yield and quality.
• Understanding chilling tolerance mechanisms is crucial for developing resilient rice cultivars.
• WRKY transcription factors play vital roles in plant stress responses.

Purpose of the Study:

• To elucidate the function of the WRKY transcription factor OsWRKY63 in rice chilling tolerance.
• To identify the molecular targets and regulatory pathways controlled by OsWRKY63.
• To explore the potential of OsWRKY63 manipulation for enhancing cold tolerance in rice.

Main Methods:

• CRISPR/Cas9 genome editing to generate OsWRKY63 knockout mutants.
• Gene expression analysis under various stress conditions (cold, dehydration, salinity, ABA).
• Subcellular localization, transcription repressor assays, molecular, biochemical, and genetic analyses.

Main Results:

• OsWRKY63 overexpression lines showed increased cold sensitivity, while knockout mutants exhibited enhanced chilling tolerance.
• OsWRKY63 acts as a nuclear transcription repressor, downregulating cold stress and reactive oxygen species scavenging genes.
• OsWRKY76 was identified as a direct target gene repressed by OsWRKY63, and OsWRKY76 is essential for cold tolerance.
• OsWRKY76 interacts with OsbHLH148 to activate OsDREB1B expression, enhancing chilling tolerance.

Conclusions:

• OsWRKY63 negatively regulates rice chilling tolerance.
• The OsWRKY63-OsWRKY76-OsDREB1B transcriptional cascade is a key pathway mediating chilling tolerance in rice.
• Targeting this pathway offers a strategy for improving cold tolerance in rice cultivars.